DC-DC converter circuits are routinely used to power DC loads in systems where the source voltage is variable and/or not matched to the loads. The converter circuit can be controlled both to regulate the output voltage (i.e., the load voltage) during normal conditions, and to limit the output current (i.e., the load current) during over-current conditions. These two control functions can be segregated to a large extent with a two-stage converter topology in which one stage is controlled to provide output voltage regulation and the other stage is controlled to provide current limiting. For example, the U.S. Pat. No. 7,336,057 to Hirabayashi discloses a two-stage converter topology in which the first-stage provides output voltage regulation, the second-stage provides output current limiting, and transformer isolation allows the second-stage to limit output current independent of the input voltage if necessary. However, the voltage regulating capability of such two-stage converters is relatively limited, and the converter must be uniquely configured for nearly every application. Accordingly, what is needed is a two-stage DC-DC conversion system having both effective current limiting capability and enhanced voltage regulating capability.